1. Field of the Invention
The present invention relates to a computer joystick, more particularly, to a computer joystick for detecting and converting displacements of its control stick into digital signals.
2. Description of the Prior Art
Computer joysticks are widely used in computer games for controlling movements of a cursor or object on a screen. A typical computer joystick comprises a housing for installing electronic and mechanical components, a vertical control stick rotatable within a fixed angle for controlling movements of the cursor on the screen, and two optical sensing devices installed at the bottom of the control stick for detecting the displacement of the control stick in different directions and converting the displacement into a corresponding displacement signal.
Please refer to FIGS. 1 and 2. FIG. 1 is a perspective view of a prior art optical sensing device 10. FIG. 2 shows a process of adjusting a detecting signal generated by the optical sensing device 10. The optical sensing device 10 comprises a circular shaped optical panel 11 comprising a plurality of light transmitting holes 12 installed around the periphery of the optical panel 11, a light source 14 installed at one side of the optical panel 11, and an optic sensor 16 installed at another side of the optical panel 11 for detecting rotations of the optical panel 11 relative to the optic sensor 16. When the optic sensor 16 receives light transmitted from the light source 14, it will generate an analog signal 18 with different amplitudes depending on the intensity of the received light. The analog signal 18 will then be converted into a digital signal 24 based on an upper limit voltage 20 and a lower limit voltage 22. As shown in FIG. 2, the upper limit voltage 20 is set at 3V, and the lower limit voltage 22 is set at 1V. The potential of the analog signal 18 exceeding 3V is defined as xe2x80x9c1xe2x80x9d, and the potential of that below 1V is defined as xe2x80x9c0xe2x80x9d. Such an arrangement will convert the peaks of the analog signal 18 into xe2x80x9c1xe2x80x9d as shown in the digital signal 24, and the troughs into xe2x80x9c0xe2x80x9d. These digital numbers are used for representing rotations of the computer joystick.
However, the aforementioned analog/digital converting method has a number of drawbacks. First, because the generation of each digital signal 24 is triggered when the voltage of the analog signal 18 reaches the upper or lower limit voltage 20, 24, and the rise and fall of the analog signal 18 from one voltage to another requires a finite amount of time, it generally takes roughly 90xcx9c120 xcexcs of time to make a change in the digital signal 24 thus making the optical sensing device 10 very unresponsive. Second, as shown in a dotted portion 26 of FIG. 2, if the computer joystick is rotated before the analog signal 26 hits the upper or lower limit voltage 20, 22, a corresponding digital signal will not be generated therefore causing the computer joystick to miss a count.
It is therefore a primary objective of the present invention to provide a computer joystick to solve the above mentioned problems.
Briefly, in a preferred embodiment, the present invention provides a computer joystick comprising:
a housing having an opening on its top;
a control stick comprising a handle installed at its top section, a ball-shaped portion at its middle section rotatably installed inside the opening of the housing, and a driving mechanism installed at its bottom section; and
two optical sensing devices for detecting movements of the driving mechanism of the control stick in two perpendicular directions and generating corresponding displacement signals, each optical sensing device comprising:
an optical panel comprising a plurality of light transmitting holes installed on it;
a light source installed at one side of the optical panel;
a plurality of sequentially arranged optic sensors installed at another side of the optical panel for detecting light transmitted from the light source through the light transmitting holes of the optical panel and generating correspondent detecting signals; and
a plurality of comparators for comparing the detecting signals to generate the displacement signals;
wherein when the handle at the top section of the control stick is moved, the driving mechanism at the bottom section of the control stick will rotate the optical panel so as to move the light transmitting holes on it, and the comparators will then compare the detecting signals generated by the optic sensors when the light transmitting holes are moved so as to generate the corresponding displacement signals.
It is an advantage of the present invention that the comparators of the computer joystick output logic high signals and logic low signals whenever the handle of the control stick moves no matter how small the movement is. Therefore, the computer joystick is very sensitive and responsive to movements of the control stick, and will not miss a count.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings.